Hey everybody -- have a 1989 Chevy Silverado 1500, inherited it from my dad. Still holding onto it because it's generally easier to work on than anything else I have, but man does it confuse me sometimes. Hard to start in the cold, requires "goosing" the throttle until it warms up. A new problem developed a couple of weeks ago, though. I can get it to start up, runs rough a little but will eventually catch and idle independently, but after about 5 minutes, an audible hissing sound starts up, SEEMS like it's coming from the passenger side of the throttle body. Consistent with this -- EVERY time I try and put it into gear, it dies without fail and then will NOT be able to be started -- almost like it is flooded. I've been working through possible problems on it.

Today I removed the throttle body and rebuilt it -- new gaskets and o-rings all around, cleaned it thoroughly, took my time and put it back together seemingly in good shape. It actually ran a little bit better/smoother after this, so that's good. I can observe the fuel injectors atomizing the fuel and spraying it into the intake(s). The hissing sound and dying upon shifting into gear remained, though. Any thoughts? I'd think vacuum lines next -- but why would the lines ALL OF A SUDDEN start hissing after about five minutes? There's no doubt that the hissing sound isn't there for the first five minutes or so. Coincidentally, I'm very, very confident it's not a radiator issue -- nothing going on there.

Any opinions or thoughts-out-loud would be appreciated. Go easy on me. I can converse "truck talk" some, but I might have to get clarification on some things.